ボルト結合部モデルの剛性および減衰能の測定と電子計算機プログラムによるシミュレーション

Abstract

In order to obtain the vibratory characteristics and quantitative values of the rigidity and damping at the bolted joint which is one of the representative joints in the machine structure, the experimental measurement was performed of a free-free beam containing a bolted joint which was excited at resonances together with the theoretical simulation of the beam by the computer program system. Recognizing that the pattern and the magnitude of the force applied to the joint are the most important factors in the analysis of the characteristics at the joint, two fundamental patterns of the applied forces were realized by using two characteristic eigenvalue modes of the model, in which the moment of forces normal to the interface and the shear forces occur exclusively at respective, test frequencies. Test results were processed to result in accurate measurements by drawing the vector loci of the frequency response. It was understood that substantial damping occurred at the pattern where the moment of the force was applied. In these measurements the damping at the joint surface was dominant over those from other sources in the model. On the other hand, at the pattern where the shearing force was applied parallel to the joint surface, damping due to the interface was not appreciable. The method to gain the quantitative values of the rigidity and damping coefficients at the joint itself by interactive use of the theoretical simulation and experiment was developed and the values at this model were identified.